The Philippines said yesterday it might file terrorism charges against three anti-China activists who planned to set off small bombs and strafe the Chinese embassy with gunfire to protest at the government's supposedly soft stance towards Beijing.

The group was led by a man named Grandeur Guerrero, who told arresting officers he was a "general" of USAFFE - the United States Armed Forces in the Far East, a second world war military formation in the Philippines.

Tipped off by an informant, agents of the National Bureau of Investigation - the investigating arm of the Department of Justice - arrested the trio on Monday morning as they were about to plant a petrol bomb in a toilet in the car park of Terminal 3 at Ninoy Aquino International Airport. The men allegedly planned to place three other bombs in the toilets of the nearby Mall of Asia.

According to the NBI's Anti-Organised Transnational Crime Division the men had four improvised devices, each consisting of a powerful firecracker taped to a plastic bottle of gasoline and improvised time fuse.

After setting off the bombs the three planned to drive past the embassy of China and shoot at the building. They planned a similar strafing run at the offices of the DMCI construction firm, a company with close links to China. NBI agents found the trio also had a pistol.

The men - aged 43, 22 and 25 - worked as security guards for a textile company just outside Manila, according to investigators, though one news report said the three were army reservists.

"We are awaiting the report of the NBI but as far as the armed forces is concerned it is not a terrorist attack….but comic relief maybe. Just getting attention." He described the incendiary device used as large illegal firecrackers used during New Year celebrations.

But in a press conference yesterday Justice Secretary Leila de Lima said the NBI was taking the matter seriously and that the men would be charged with illegal possession of incendiary devices, and possibly conspiracy to commit terrorism. Both are non-bailable offences.

She said counterterrorist experts reported the bombs would have created large fireballs that could have killed or injured anyone within five to 10 metres.

"They claim to be defenders of the Filipino people and consider China and (Filipino-Chinese) oligarch taipans' monopolistic business practices and illegal mining as enemies," she said.

One of the seized items was a manifesto in Tagalog which the group planned to issue after the bombings. Titled "Manifesto of the Movement against Fear", it said: "It's time to show China and the international community...that we are ready to fight for our rights and sovereignty even if this means sacrificing our lives."

De Lima called the arrested men "misguided elements of our society" and hinted there might be a deeper plot.

"We have an idea how big they are, based on informants but we want to validate it first," she said.

The Mall of Asia is owned by Henry Sy, the Philippines' richest man, who was born in China.

DMCI is owned by David Consunji, another ethnic-Chinese Filipino whom Forbes magazine lists as the country's sixth richest man.

The Philippines and China are engaged in maritime territorial disputes, including at Scarborough Shoal - referred to in China as Huangyan Island - which is patrolled by Chinese vessels.

Catapang denied that the Philippines had lost territory to China: "I'd like to say we have not lost control of the Scarborough Shoal...We're just awaiting the decision of the United Nations".